The head of the U.S. central bank says the economy is growing more slowly than expected, but says growth will pick up early next year.

Federal Reserve Chairman Ben Bernanke told journalists that the slower growth is due to temporary problems such as the disruptions caused by Japan's earthquake and an increase in gasoline prices.

Fed experts now expect around 2.8 percent growth this year, which is about four-tenths of a percentage points lower than earlier estimates.

The economic assessment comes after two days of consultations among top bank officials and follows several disappointing economic reports.

Fed officials voted to keep interest rates steady in the ultra-low range where they have been for some time.

They also decided to end another program to stimulate the economy that purchased large quantities of financial assets with the intention of lowering long-term interest rates.